.\" $OpenBSD: X509_get_pubkey.3,v 1.13 2022/03/31 17:27:17 naddy Exp $
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.Dd $Mdocdate: March 31 2022 $
.Dt X509_GET_PUBKEY 3
.Os
.Sh NAME
.Nm X509_get_pubkey ,
.Nm X509_get0_pubkey ,
.Nm X509_set_pubkey ,
.Nm X509_get_X509_PUBKEY ,
.Nm X509_get0_pubkey_bitstr ,
.Nm X509_REQ_get_pubkey ,
.Nm X509_REQ_get0_pubkey ,
.Nm X509_REQ_set_pubkey ,
.Nm X509_extract_key ,
.Nm X509_REQ_extract_key
.Nd get or set certificate or certificate request public key
.Sh SYNOPSIS
.In openssl/x509.h
.Ft EVP_PKEY *
.Fo X509_get_pubkey
.Fa "X509 *x"
.Fc
.Ft EVP_PKEY *
.Fo X509_get0_pubkey
.Fa "const X509 *x"
.Fc
.Ft int
.Fo X509_set_pubkey
.Fa "X509 *x"
.Fa "EVP_PKEY *pkey"
.Fc
.Ft X509_PUBKEY *
.Fo X509_get_X509_PUBKEY
.Fa "const X509 *x"
.Fc
.Ft ASN1_BIT_STRING *
.Fo X509_get0_pubkey_bitstr
.Fa "const X509 *x"
.Fc
.Ft EVP_PKEY *
.Fo X509_REQ_get_pubkey
.Fa "X509_REQ *req"
.Fc
.Ft EVP_PKEY *
.Fo X509_REQ_get0_pubkey
.Fa "X509_REQ *req"
.Fc
.Ft int
.Fo X509_REQ_set_pubkey
.Fa "X509_REQ *x"
.Fa "EVP_PKEY *pkey"
.Fc
.Ft EVP_PKEY *
.Fo X509_extract_key
.Fa "X509 *x"
.Fc
.Ft EVP_PKEY *
.Fo X509_REQ_extract_key
.Fa "X509_REQ *req"
.Fc
.Sh DESCRIPTION
.Fn X509_get_pubkey
attempts to decode the public key for certificate
.Fa x .
If successful, it returns the public key as an
.Vt EVP_PKEY
pointer with its reference count incremented: this means the returned
key must be freed up after use.
.Fn X509_get0_pubkey
is similar except that it does not increment the reference count
of the returned
.Vt EVP_PKEY ,
so it must not be freed up after use.
.Pp
.Fn X509_get_X509_PUBKEY
returns an internal pointer to the
.Vt SubjectPublicKeyInfo
structure contained in
.Fa x .
The returned value must not be freed up after use.
.Pp
.Fn X509_get0_pubkey_bitstr
returns an internal pointer to just the public key contained in this
.Vt SubjectPublicKeyInfo
structure, without the information about the algorithm used.
.Pp
.Fn X509_set_pubkey
attempts to set the public key for certificate
.Fa x
to
.Fa pkey .
The key
.Fa pkey
should be freed up after use.
.Pp
.Fn X509_REQ_get_pubkey ,
.Fn X509_REQ_get0_pubkey ,
and
.Fn X509_REQ_set_pubkey
are similar but operate on certificate request
.Fa req .
.Pp
The first time a public key is decoded, the
.Vt EVP_PKEY
structure is cached in the certificate or certificate request itself.
Subsequent calls return the cached structure with its reference count
incremented to improve performance.
.Pp
.Fn X509_extract_key
and
.Fn X509_REQ_extract_key
are deprecated aliases for
.Fn X509_get_pubkey
and
.Fn X509_REQ_get_pubkey ,
respectively, implemented as macros.
.Sh RETURN VALUES
.Fn X509_get_pubkey ,
.Fn X509_get0_pubkey ,
.Fn X509_get_X509_PUBKEY ,
.Fn X509_get0_pubkey_bitstr ,
.Fn X509_REQ_get_pubkey ,
.Fn X509_REQ_get0_pubkey ,
.Fn X509_extract_key ,
and
.Fn X509_REQ_extract_key
return a public key or
.Dv NULL
if an error occurred.
.Pp
.Fn X509_set_pubkey
and
.Fn X509_REQ_set_pubkey
return 1 for success or 0 for failure.
.Pp
In some cases of failure of
.Fn X509_get0_pubkey ,
.Fn X509_set_pubkey ,
.Fn X509_REQ_get_pubkey ,
.Fn X509_REQ_get0_pubkey ,
and
.Fn X509_REQ_set_pubkey ,
the reason can be determined with
.Xr ERR_get_error 3 .
.Sh ERRORS
.Fn X509_get_pubkey ,
.Fn X509_get0_pubkey ,
.Fn X509_REQ_get_pubkey ,
.Fn X509_extract_key ,
and
.Fn X509_REQ_extract_key
provide diagnostics as documented for
.Xr X509_PUBKEY_get 3 .
If
.Fa x
or
.Fa req
is
.Dv NULL
or contains no certificate information,
they fail without pushing an error onto the stack.
.Pp
.Fn X509_get_X509_PUBKEY
provides no diagnostics and crashes by accessing a
.Dv NULL
pointer if
.Fa x
is
.Dv NULL
or contains no certificate information,
.Pp
.Fn X509_get0_pubkey_bitstr
provides no diagnostics
and fails without pushing an error onto the stack if
.Fa x
is
.Dv NULL ,
but it crashes by accessing a
.Dv NULL
pointer if
.Fa x
contains no certificate information.
.Sh SEE ALSO
.Xr d2i_X509 3 ,
.Xr X509_CRL_get0_by_serial 3 ,
.Xr X509_NAME_add_entry_by_txt 3 ,
.Xr X509_NAME_ENTRY_get_object 3 ,
.Xr X509_NAME_get_index_by_NID 3 ,
.Xr X509_NAME_print_ex 3 ,
.Xr X509_new 3 ,
.Xr X509_PUBKEY_new 3 ,
.Xr X509_REQ_new 3 ,
.Xr X509_sign 3 ,
.Xr X509_verify_cert 3 ,
.Xr X509V3_get_d2i 3
.Sh STANDARDS
RFC 5280, Internet X.509 Public Key Infrastructure Certificate
and Certificate Revocation List (CRL) Profile,
section 4.1 Basic Certificate Fields
.Pp
RFC 2986: PKCS #10: Certification Request Syntax Specification,
section 4.1 CertificationRequestInfo
.Sh HISTORY
.Fn X509_extract_key
and
.Fn X509_REQ_extract_key
first appeared in SSLeay 0.5.1 but returned a pointer to an
.Vt RSA
object before SSLeay 0.6.0.
.Fn X509_get_pubkey ,
.Fn X509_set_pubkey ,
.Fn X509_REQ_get_pubkey ,
and
.Fn X509_REQ_set_pubkey
first appeared in SSLeay 0.6.5.
.Fn X509_get_X509_PUBKEY
first appeared in SSLeay 0.8.0.
These functions have been available since
.Ox 2.4 .
.Pp
.Fn X509_get0_pubkey_bitstr
first appeared in OpenSSL 0.9.7 and has been available since
.Ox 3.4 .
.Pp
.Fn X509_get0_pubkey
first appeared in OpenSSL 1.1.0 and has been available since
.Ox 6.3 .
.Fn X509_REQ_get0_pubkey
first appeared in OpenSSL 1.1.0 and has been available since
.Ox 7.1 .
